The present invention relates to apparatus for sensing the total pressure of a moving fluid, and more particularly to such apparatus having improved means for removing turbulence from the fluid prior to impact thereof with the sensing means.
Many forms of apparatus have been provided for sensing and measuring the pressure of fluids flowing through enclosed ducts or conduits. It is generally necessary to provide some means upstream of the sensing location for minimizing turbulence in order to insure reliable readings, particularly in the case of total pressure measurement. In the case of air flow measurement, the most common straightener means employed in the prior art is a honeycomb structure or other such vanes having surfaces extending in the direction of air flow and arranged across the interior of the duct or conduit a suitable distance upstream from the sensor locations. Thus, the fluid is flowing essentially parallel to the axis of the duct as it reaches the sensors.
While prior art straightener means of the aforementioned type serve to remove turbulence from the flow in a satisfactory manner, their presence results in a significant drop in static pressure due to the added resistance to flow. This pressure drop is, of course, undesirable in virtually all applications since it is accompanied by a loss of energy in the fluid flow. Among the most common applications of the invention is the measurement of air flow in heating, ventilating and air conditioning systems. Typical examples of equipment used in such applications, including references to prior art flow straightener means, are found in applicant's copending U.S. application Ser. No. 580,153.
It is a principal object of the present invention to provide fluid pressure measurement apparatus having improved flow straightener means upstream of fixed sensor locations.
A further object is to provide flow straightener means which produce minimal loss in static pressure.
Another object is to provide apparatus for measuring both total and static pressure by a plurality of sensing probes fixedly positioned in a transverse plane of the duct carrying the fluid wherein means for straightening the flow of fluid prior to reaching the total pressure probes are supported by the static pressure probes.
Other objects will in part be obvious and will in part appear hereinafter.